Flood-Guard operates like a check valve to seal off water back-up caused by overloaded sewers. Water flows normally through the drain until the sewer begins to back up. Then the Flood-Guard float rises to seal off the drain opening until the water recedes. A screwdriver and a couple of minutes are all you need to install a Flood-Guard. Once in place, it can prevent property damage and a very messy clean-up job. Gaskets are made of molded rubber, and all metal parts are plated or stainless steel.